Telephone drop wire



y 26, 1 E. s. GEORGE 3,134,845

TELEPHONE DROP WIRE Filed Feb. 13, 1961 PRIOR ART JACKET 0. g. usonzul 16 c ounuc-ron Iii-muses! INSULATION A7 TORNE Y3 United States Patent 3,134,845 TELEPHGNE DRQP WIRE Edward S. George, New Brunswick, N..l., assigner to General Cable Corporatien, New York, N.Y., a corporatien or New Jersey Filed Feb. 13, 1961, den. Nu. 39,4l5ti 1 Claim. (Ci. 174-417) This invention relates to an improved telephone drop wire.

Telephone drop wire, known to the art, comprises two rubber insulated strands bound together and reinforced by an overlying cotton braid or wrap. The assembly is then covered with a neoprene jacket.

Added strength is always desirable in drop wire construction.

Further, with conventional drop wire, terminations are a weak point. When the jacket is slit to separate the strands, the strand insulation is exposed to the attack of, for example, ozone.

It is, therefore, one object of this invention to provide an improved drop wire construction having higher static load strength.

It is a further object of this invention to provide an improved drop wire construction having greater resistance toozone attack at termination points.

This invention will be more clearly understood by reference to the following description taken in conjunction with the accompanying drawings, of which:

FIG. 1 is a cross-section view of drop wire in accordance with the construction of the prior art; and

FIG. 2 is a cross-section view of drop wire constructed in accordance with the present invention.

In FIG. 1 there is shown a conventional telephone drop wire comprising parallel insulated strands consisting of conductors 10, 12, each of which is covered by synthetic rubber insulation 14. The conductors are laid parallel in an overall cotton braid or wrap 16. The assembly is completed by a covering jacket 18, as, for example, of

neoprene.

In FIG. 2 there is shown a drop wire construction in accordance with the present invention comprising parallel strands consisting of conductors 10, 12, such as #18 AWG copper covered steel, 30% conductivity covered with synthetic rubber insulator 14. A wrap 20 is applied over each strand. This wrap is preferably a parallel wrap such as a cotton wrap of #20 cotton, 2-ply, 16 ends, 2.5" lay over each insulated conductor.

The wrapped strands are covered by a dumbbell-shaped neoprene jacket 22. The jacket encases each strand by a concentric jacket, joined by web 24.

The assembly in accordance with this invention retains the desired performance characteristics of good impact and abrasion resistance and excellent compression resistance. In addition, the construction in accordance with this invention affords excellent ozone protection at termination points. The two conductors may be separated by slitting the Web 24 of the dumbbell jacket with a conventional wire slitter whereupon the individual conductors may be separated with a protective neoprene covering over the rubber insulation of each strand.

The construction in accordance with this invention has greatly improved static load breaking strength. Under static load, the cable constructed in accord-ance with this invention held 450 lbs. for 120 minutes and broke when the load was gradually increased to 480 lbs. On the other hand, the cable constructed in accordance with the prior art failed with a load of 450 lbs. after minutes. In the failure, both the jacket and the insulation ruptured and stripped clean of the conductor.

This invention may be variously embodied and modified within the scope of the subjoined claim.

What is claimed is:

A telephone drop wire comprising a first strand including a conductor coated with electrical insulation, a second strand also including a conductor coated with electrical insulation, the insulation on the first and second strands being synthetic rubber insulation having good impact and abrasion resistance, and excellent compression resistance, a separate reinforcing wrap applied over each of the insulated strands and substantially concentric with the conductor, the insulated and wrapped strands being disposed parallel to one another so that projections of the conductors on an underlying plane are straight and parallel lines, a neoprene jacket of dumbbell-shaped cross section encasing both of the wrapped insulated strands, said jacket in said cross section including enlarged end portions each encasing one of the wrapped strands and being substantially concentric with the conductor and providing a wall for protecting the rubber from ozone at termination points, and the enlarged concentric portions of the jacket being joined by a web composed entirely of the same material as the concentric portions of the jacket, the web having top and bottom surfaces between the end portions of the jacket and forming the stem of the dumbbell cross section, said web spacing the wrapped strands from one another by a distance substantially equal to at least twice the radial thickness of the neoprene wall in each of the enlarged end sections of the dumbbell cross section so that the two strands may be slit apart lengthwise of the web and separated leaving each of the strands with its insulation, and reinforcing wrap unimpaired and leaving the neoprene jacket of substantial thickness around the entire circumference of each of the strands throughout the length of such separation, whereby the rubber insulation of both strands is protected against ozone at terminations of the wire.

References Cited in the file of this patent UNITED STATES PATENTS 1,729,160 Engle Sept. 24, 1929 2,544,233 Kennedy Mar. 6, 1951 2,628,998 Frisbie Feb. 17, 1953 2,663,755 McBride Dec. 22, 1953 FOREIGN PATENTS 815,207 Germany Oct. 1, 1951 

